What makes a parent?

My sister and I watched the movie Chaos Theory a couple nights ago.  It has Ryan Reynolds in it and he's pretty entertaining.  The movie took a twist I wasn't expecting however.  *Spoiler Alert*  The man is organized to the extreme and his wife sets his watch back 10 minutes as a joke.  Anyway it screws up his whole schedule and day and through a series of events he discovers that his 7 year old daughter isn't his genetic child.  He comes to find out he has Klinefelter's Syndrome which in the movie the doctor tells him makes him completely sterile (although wikipedia states it causes reduced fertility not sterility).  Anyway apparently his wife did not realize it wasn't his child either so it wasn't like she was lying to him.  During one scene he confronts his wife about it and asks about the little girl "Who is her father?" and the wife keeps saying "You are" and giving examples of things he has done for his daughter...staying up nights with her during a fever, supporting her school work, adoring her as a baby and all of these things.  It kind of made me teary and sad for his character in relating to finding out that kind of knowledge in such a way.  But at the same time reinforced the idea that the father/mother or parent is the one that steps in and takes care of, adores and raises the child.  It doesn't discredit that someone else's genetics are involved but it also gives credit to (hopefully) what makes a parent and who a child will consider their mom or dad.

It also makes it easier to understand the importance of being honest with a child's history and makeup.  Although this story makes it seem that all parties involved were unaware of things playing out how they did.  I just couldn't imagine a child finding out that kind of information later in life and how confusing and emotional that would be.  We are in the "tell camp" when it comes to donor egg in vitro.  I guess you never know what is the right way to handle things or how a child will take this information but I hope that we are going into this with a clear head and I hope that keeping it simple and forthright will make it easier to understand and accept for our girls.